From: Bjorn Helgaas <bhelgaas@google.com> To: Ingo Molnar <mingo@kernel.org> Cc: "Luis R. Rodriguez" <mcgrof@suse.com>, "Luis R. Rodriguez" <mcgrof@do-not-panic.com>, bp@suse.de, arnd@arndb.de, luto@amacapital.net, akpm@linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, tomi.valkeinen@ti.com, mst@redhat.com, toshi.kani@hp.com, linux-fbdev@vger.kernel.org, xen-devel@lists.xensource.com, benh@kernel.crashing.org Subject: Re: [PATCH v9 0/8] pci: add pci_iomap_wc() and pci_ioremap_wc_bar() Date: Wed, 22 Jul 2015 08:43:48 -0500 [thread overview] Message-ID: <20150722134348.GA10966@google.com> (raw) In-Reply-To: <20150722083844.GA14626@gmail.com> Hi Ingo, On Wed, Jul 22, 2015 at 10:38:45AM +0200, Ingo Molnar wrote: > > * Bjorn Helgaas <bhelgaas@google.com> wrote: > > > > > > Let me know if these are OK or if there are any questions. > > > > > > > > > > [0] http://lkml.kernel.org/r/20150625204703.GC4898@pd.tnic > > > > > [1] http://lkml.kernel.org/r/20150707095012.GQ7021@wotan.suse.de > > > > > > > > Ingo, > > > > > > > > Just a friendly reminder. Let me know if there are any issues or questions. > > > > > > It would be nice to get an Acked-by from Bjorn for the PCI API bits. > > > > I think the actual code of pci_ioremap_wc() and pci_ioremap_wc_bar() is fine > > (although I might have named it pci_ioremap_bar_wc() for consistency). > > > > I declined to merge or ack them myself because they're obvious extensions of > > pci_ioremap() and pci_ioremap_bar(), and I would prefer that they be exported > > the same way, i.e., with EXPORT_SYMBOL(), not EXPORT_SYMBOL_GPL(). > > Huh? AFAICS pci_ioremap_bar() has been a _GPL export for a long time: > ... > (ioremap_wc() is EXPORT_SYMBOL() mostly by accident, it's the odd one out.) You're right, I was mistaken about pci_ioremap_bar(). But I'm not convinced yet that ioremap_wc() is the odd one out. All the interfaces I found, with the exception of ioremap_uc() on x86 and pci_ioremap_bar(), are EXPORT_SYMBOL(), even the _wc and _wt flavors. > Also, FWIIW: I personally got essentially zero feedback and help from proprietary > binary kernel module vendors in the past couple of years as x86 maintainer, > despite a fair chunk of kernel crashes reported on distro kernels occuring in > them... > > Based on that very negative experience, when we introduce something as complex and > as critical as new caching APIs, the last thing I want is to have obscure bugs in > binary modules I cannot fix in any reasonable fashion. So even if the parent APIs > of new APIs weren't already _GPL exports (as in this case), I'd export them as > _GPL in this case. > > > I think using EXPORT_SYMBOL_GPL to express individual political aims rather than > > as a hint about what might be derived work makes us look like zealots, and > > that's not my style. > > As far as I'm concerned it's a pure technological choice: I don't want to export > certain types of hard to fix and critical functionality to drivers that I cannot > then fix. That's a good argument that I hadn't heard before (or possibly it was there and I missed it). It would be stronger still if we could change the parent APIs similarly. If a proprietary driver can't use pci_ioremap_wc() because it's exported _GPL, it's trivial to use ioremap_wc() directly. Bjorn
WARNING: multiple messages have this Message-ID (diff)
From: Bjorn Helgaas <bhelgaas@google.com> To: Ingo Molnar <mingo@kernel.org> Cc: "Luis R. Rodriguez" <mcgrof@suse.com>, "Luis R. Rodriguez" <mcgrof@do-not-panic.com>, bp@suse.de, arnd@arndb.de, luto@amacapital.net, akpm@linux-foundation.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, tomi.valkeinen@ti.com, mst@redhat.com, toshi.kani@hp.com, linux-fbdev@vger.kernel.org, xen-devel@lists.xensource.com, benh@kernel.crashing.org Subject: Re: [PATCH v9 0/8] pci: add pci_iomap_wc() and pci_ioremap_wc_bar() Date: Wed, 22 Jul 2015 13:43:48 +0000 [thread overview] Message-ID: <20150722134348.GA10966@google.com> (raw) In-Reply-To: <20150722083844.GA14626@gmail.com> Hi Ingo, On Wed, Jul 22, 2015 at 10:38:45AM +0200, Ingo Molnar wrote: > > * Bjorn Helgaas <bhelgaas@google.com> wrote: > > > > > > Let me know if these are OK or if there are any questions. > > > > > > > > > > [0] http://lkml.kernel.org/r/20150625204703.GC4898@pd.tnic > > > > > [1] http://lkml.kernel.org/r/20150707095012.GQ7021@wotan.suse.de > > > > > > > > Ingo, > > > > > > > > Just a friendly reminder. Let me know if there are any issues or questions. > > > > > > It would be nice to get an Acked-by from Bjorn for the PCI API bits. > > > > I think the actual code of pci_ioremap_wc() and pci_ioremap_wc_bar() is fine > > (although I might have named it pci_ioremap_bar_wc() for consistency). > > > > I declined to merge or ack them myself because they're obvious extensions of > > pci_ioremap() and pci_ioremap_bar(), and I would prefer that they be exported > > the same way, i.e., with EXPORT_SYMBOL(), not EXPORT_SYMBOL_GPL(). > > Huh? AFAICS pci_ioremap_bar() has been a _GPL export for a long time: > ... > (ioremap_wc() is EXPORT_SYMBOL() mostly by accident, it's the odd one out.) You're right, I was mistaken about pci_ioremap_bar(). But I'm not convinced yet that ioremap_wc() is the odd one out. All the interfaces I found, with the exception of ioremap_uc() on x86 and pci_ioremap_bar(), are EXPORT_SYMBOL(), even the _wc and _wt flavors. > Also, FWIIW: I personally got essentially zero feedback and help from proprietary > binary kernel module vendors in the past couple of years as x86 maintainer, > despite a fair chunk of kernel crashes reported on distro kernels occuring in > them... > > Based on that very negative experience, when we introduce something as complex and > as critical as new caching APIs, the last thing I want is to have obscure bugs in > binary modules I cannot fix in any reasonable fashion. So even if the parent APIs > of new APIs weren't already _GPL exports (as in this case), I'd export them as > _GPL in this case. > > > I think using EXPORT_SYMBOL_GPL to express individual political aims rather than > > as a hint about what might be derived work makes us look like zealots, and > > that's not my style. > > As far as I'm concerned it's a pure technological choice: I don't want to export > certain types of hard to fix and critical functionality to drivers that I cannot > then fix. That's a good argument that I hadn't heard before (or possibly it was there and I missed it). It would be stronger still if we could change the parent APIs similarly. If a proprietary driver can't use pci_ioremap_wc() because it's exported _GPL, it's trivial to use ioremap_wc() directly. Bjorn
next prev parent reply other threads:[~2015-07-22 13:43 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-07-09 1:54 [PATCH v9 0/8] pci: add pci_iomap_wc() and pci_ioremap_wc_bar() Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 1/8] PCI: Add pci_ioremap_wc_bar() Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 2/8] drivers/video/fbdev/i740fb: Use arch_phys_wc_add() and pci_ioremap_wc_bar() Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 3/8] drivers/video/fbdev/kyrofb: " Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 4/8] drivers/video/fbdev/gxt4500: Use pci_ioremap_wc_bar() to map framebuffer Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 5/8] PCI: Add pci_iomap_wc() variants Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 6/8] drivers/video/fbdev/arkfb.c: Use arch_phys_wc_add() and pci_iomap_wc() Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 7/8] drivers/video/fbdev/s3fb: " Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` [PATCH v9 8/8] drivers/video/fbdev/vt8623fb: " Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-09 1:54 ` Luis R. Rodriguez 2015-07-17 20:29 ` [PATCH v9 0/8] pci: add pci_iomap_wc() and pci_ioremap_wc_bar() Luis R. Rodriguez 2015-07-17 20:29 ` Luis R. Rodriguez 2015-07-21 8:52 ` Ingo Molnar 2015-07-21 8:52 ` Ingo Molnar 2015-07-21 8:52 ` Ingo Molnar 2015-07-21 13:21 ` Bjorn Helgaas 2015-07-21 13:21 ` Bjorn Helgaas 2015-07-22 8:38 ` Ingo Molnar 2015-07-22 8:38 ` Ingo Molnar 2015-07-22 13:43 ` Bjorn Helgaas [this message] 2015-07-22 13:43 ` Bjorn Helgaas 2015-08-06 21:45 ` Luis R. Rodriguez 2015-08-06 21:45 ` Luis R. Rodriguez
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